Arrangement for feeding rod shaped workpieces to a machine tool

ABSTRACT

An arrangement for feeding rod-shaped workpieces to a machine tool comprises an elongated hollow guide member for accommodating a respective workpiece therein. A support structure extends longitudinally of the guide member and surrounds the same with spacing, and a plurality of elongated elastically yieldable members extends longitudinally of the guide member in the spacing and supports the guide member in the support structure. The oscillations to which the guide member is subjected during the operation of the arrangement are damped by the elastically yieldable members so that they are not transmitted to the support structure. The elastically yieldable members may be hollow tubes into which a pressurized medium is introduced, and the pressure of the medium may be adjusted so as to correspond to the various working conditions. The guide member and the support structure may be constituted by several coextensive sections, the sections of the support structure being mounted on one another for pivoting about an axis which extends parallel to the elongation of the sections between an open position in which the workpiece can be introduced into the guide member and a closed position. A control arrangement is also disclosed which controls the pressure inside the hollow tubes and interrupts the electric circuit of the machine tool as long as the pressure inside the hollow tubes is below a threshold value.

BACKGROUND OF THE INVENTION

The present invention relates to a feeding arrangement, and moreparticularly to an arrangement for feeding rod-shaped workpieces to amachine tool.

There are already known various machine tools, in particular lathes,which perform material-removing operations on rod-shaped workpieces. Inconnection with such machine tools, it is already known to support therod-shaped workpiece along its length, particularly by accommodating therod-shaped workpiece in a tubular guide member. Experience with thistype of arrangement has shown that, especially when the workpiecerotates in the guide member, the latter is subjected to oscillationswhich, when the guide member is rigidly mounted on a support structure,are transmitted to such support structure and via the same to theenvironment of the machine tool, which is a very undesirable situation.

In order to avoid this disadvantage, it is already known to provide afeeding arrangement in which such oscillations are damped so that theirtransmission to the support structure is avoided. In one of suchconventional arrangements, the support structure includes a jacket tubeand a guide member is accommodated in the jacket tube with spacingtherefrom, the spacing being filled with a flowable material,particularly sand. The edge portions of the jacket tube and the guidemember are rigidly and sealingly connected to one another so as toprevent the flowable material from escaping from the spacing. However,this arrangement is disadvantageous in several respects. First of all,the connection of the end portions of the jacket tube and the guidemember to one another constitutes oscillation transmitting bridges whichimpair the oscillation damping characteristic of this arrangement.Furthermore, when it is necessary to substitute a new guide member forthe one previously used, either because the previous guide member hasbeen worn out, or because it is desired to feed rod-shaped workpieces ofdifferent diameters into the machine tool, it is necessary to replacethe entire assembly. This, of course, is very disadvantageous because itrequires keeping in stock a plurality of such complete assemblies,rather than just an assortment of guide members of different diameters.

SUMMARY OF THE INVENTION

It is a general object of the present invention to avoid thedisadvantages of the prior art arrangements.

It is a further object of the present invention to provide anarrangement for feeding rod-shaped workpieces to a machine tool whicharrangement possesses excellent oscillation-damping characteristics.

It is a still further object of the present invention to provide afeeding arrangement in which all oscillation transmitting bridges areeliminated.

It is yet another object of the present invention to provide a feedingarrangement in which the damping behavior can be adjusted to suitvarious working conditions.

It is a concomittant object of the present invention to provide afeeding arrangement for machine tools which permits simple replacementof the workpiece guide member.

Still another object of the present invention is to provide a feedingarrangement which simplifies the introduction of the rod-shapedworkpieces into the guide member.

In pursuance of these objects and others which will become apparenthereafter, one feature of the present invention resides, in anarrangement for feeding rod-shaped workpieces to a machine tool, in acombination comprising an elongated hollow guide member foraccommodating a workpiece therein; support means extendinglongitudinally of the guide member and surrounding the same withspacing; and a plurality of elongated elastically yieldable membersextending longitudinally of the guide member in said spacing andoperative for supporting the guide member in the support means and fordamping oscillations to which the guide member is subjected during theoperation of the arrangement so as to prevent transmission of theoscillations to said support means.

In a currently preferred embodiment of the present invention, theelastically yieldable members are hollow tubes which are filled withpressurized medium.

It is currently preferred that the hollow tubes of elastically yieldablematerial extend parallel to the guide member and be filled with agaseous medium such as air, or a fluid medium, such as oil of highviscosity. The pressure of the pressurized medium in the hollow tubescan be varied in order to obtain excellent oscillation damping atvarious frequencies of the oscillating movements. The guide member, e.g.a tube, is supported on the hollow tubes of elastically yieldablematerial in such a manner that it can be removed from the arrangementand substituted by another guide member when the pressure inside thehollow tubes has been relieved. Thus, the arrangement of the presentinvention is very versatile and the replacement of the guide member by adifferent one is a very simple operation.

According to another currently preferred embodiment of the presentinvention, the guide member as well as the jacket which surrounds thesame with spacing and which forms part of the support structure areconstituted by several coextensive sections, each of the sections of theguide tube being supported by said elastically yieldable hollow tubes inone of the sections of the jacket, and the jacket sections are mountedon one another for displacement with respect to each other so as topermit displacement of the sections between an open position in which aworkpiece can be introduced into the guide member, and a closed positionin which the guide member completely surrounds the workpiece.Preferably, the sections are mounted on one another for pivoting aboutan axis which extends parallel to the elongation of the guide member andan arrangement is provided which pivots at least one of the sections ofthe jacket about such axis between the open and the closed position. Anarrangement may be provided for introducing the workpieces into theguide member when the sections are in their open position.

Another important feature of the present invention resides in theprovision of a pressure switch which controls the electric circuit ofthe machine tool in such a manner that the electric circuit isinterrupted as long as the pressure inside the hollow tubes supportingthe guide member is below a threshold value.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side elevational view of a first embodiment of the presentinvention;

FIG. 2 is a top plan view of the embodiment of FIG. 1;

FIG. 3 is a cross-sectional view taken on line III--III of FIG. 1;

FIG. 4 is an enlarged cross-sectional view taken on line IV--IV of FIG.1;

FIG. 5 is a diagrammatic view similar to FIG. 4 and illustrating thepressurized medium feeding and withdrawing arrangement;

FIG. 6 is a side elevational view of another embodiment of the presentinvention;

FIG. 7 is a top plan view of the embodiment of FIG. 6;

FIG. 8 is an enlarged cross-sectional view taken on line VIII--VIII ofFIG. 6;

FIG. 9 is a diagrammatic view similar to FIG. 8, and illustrating thepressurized medium supplying and withdrawing arrangement; and

FIG. 10 is an enlarged exploded cross-sectional view illustrating theconnection of one of the hollow tubes with the jacket.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and first to FIGS. 1 - 5 which illustrateone embodiment of the arrangement of the present invention, it may beseen therein that the machine tool has been assigned a general referencecharacter A, while the assembled arrangement of the present invention isdesignated in general by reference character B. The machine tool A is ofa conventional construction, so that it need not be discussed in detail.It is only pointed out that this machine tool includes an arrangementfor advancing the rod-shaped workpiece 23 longitudinally thereof. Thefeeding arrangement B, as best seen in FIG. 4, includes acircumferentially complete one-piece jacket tube 1 which surrounds withspacing a guide member 4 of tubular configuration. A plurality of hollowtubes of elastically yieldable material, which are designated withreference numerals 5, 6, 7 and 8, is located around the guide member 4and supports the same in the jacket 1 concentrically thereto. A guidemember 4 and the hollow tubes 5, 6, 7 and 8 extend parallel to thejacket tube 1 over the entire length thereof. The hollow tubes 5, 6, 7and 8 are made of an elastic material such as rubber, and are closed attheir ends which face the machine tool A. As illustrated in FIGS. 1 - 3the assembly B is supported on two supports 2 and 3 for pivoting about avertical axis on the support 2 and for sliding over a substantiallyhorizontal surface 13 on the support 3. In the position of thearrangement B that is illustrated in FIG. 2 in full lines, thearrangement is ready for feeding the rod-shaped workpiece to the machinetool A, while a rod shaped workpiece can be inserted into the guide tube4 from the end of the arrangement B which faces the machine tool A whenthe arrangement B is in its dash-dotted position. A conduit 9communicates with the hollow tubes 5, 6, 7 and 8 at the ends which aredistant from the machine tool A.

The conduit 9 is part of a hydraulic or pneumatic system which isillustrated in more detail in FIG. 5.

Such a system includes a source of pressurized medium which includes apump 11, and in the illustrated hydraulic embodiment of the presentinvention, also a reservoir 14 for the hydraulic fluid. Of course, whenthe pressurized medium used in the system is air, the reservoir 14 canbe omitted, and the inlet side of the pump may communicate with theambient atmosphere.

The pressurized medium system further includes a three-positionfour-port valve 10 which is mounted for movement between three positionsdesignated as E, O, D. Such a valve 10 is of conventional constructionso that its operation need not be discussed in any great detail. Itsuffices to say that in the illustrated position 0 the communication ofthe conduit 9 with the pump 11 is interrupted, as is the communicationof the conduit 9 with the reservoir 14. On the other hand, when thevalve 10 is moved toward the right, that is into the position D, theconduit 9 will communicate with the outlet side of the pump 11 and thepressurized medium will be delivered to the hollow tubes 5, 6, 7 and 8.Conversely, in the position E, the conduit 9 will communicate with theinlet side of the pump 11 and with the reservoir 14 so that the pressurein the hollow tubes 5, 6, 7 and 8 will be relieved.

A pressure measuring device 12 communicates with the conduit 9 andindicates the pressure prevailing therein and thus in the hollow tubes5, 6, 7 and 8. A pressure operated switch 16 also communicates with theconduit 9 and has a contact element 15 interposed in the electriccircuit of the machine tool. When the pressure in the conduit 9 and thusin the hollow tubes 5, 6, 7 and 8 is below a certain preselected minimumvalue, the contact element 15 is opened and thus the machine tool Acannot be energized. On the other hand, once the pressure in the conduit9 exceeds a threshold value, the contact element 15 closes the circuitof the machine tool A, and operation of the latter can be commenced.

It will be appreciated from the above discussion of the structure of thearrangement B that, when the guide member 4 is to be substituted by adifferent guide member, the pressure in the hollow tubes 5, 6, 7 and 8is relieved by moving the three-position four-port valve into itsposition E so that the guide member can be easily removed from thejacket 1 longitudinally thereof, and another guide member 4 introducedinstead. Once the guide member 4 is properly introduced into the jacket1, the valve 10 is moved to its position D so that the pressurizedmedium is introduced via the conduit 9 into the hollow tubes 5, 6, 7 and8 which expand and center the guide member 4 with respect to thejacket 1. By controlling the pressure in the conduit 9 which may beascertained from the measuring device 12, it is possible to give thehollow tubes 5, 6, 7 and 8 such oscillation damping characteristics asto prevent the transmission of the oscillations to the jacket 1 at anyfrequency of oscillation. In this connection, it should be mentionedthat the oscillations will be damped regardless of their origin, butthat this arrangement is particularly advantageous for dampingoscillations which result from the rotation of the rod-shaped workpiecein the guide member 4.

It will be seen that this embodiment of the present invention isparticularly simple and satisfies all of the above-mentionedrequirements, particularly the requirement for simple replacement of theguide member 4, the requirement for adjusting the oscillation-dampingcharacteristics of the elastically yieldable members supporting theguide member and the requirement for simple construction and operationof the arrangement.

The embodiment of the arrangement C of the present invention illustratedin FIGS. 6 to 10 is in many respects similar to that discussed inconnection with FIGS. 1 - 5, so that similar reference numerals havebeen used to designate similar parts of the arrangement C. In thisembodiment, the machine tool A does not have any arrangement foradvancing the rod-shaped workpiece 23 longitudinally thereof, so that anadvancing arrangement 43 is provided which forms part of the arrangementC. The advancing arrangement 43 is of a conventional design so that itwill not be described in any detail. It is sufficient to say that itincludes a motor which drives a pulley, and and an endless element ismoved when the pulley rotates and advances the workpiece 23 in thearrangement C.

As illustrated in FIG. 8, the support structure or jacket of thisembodiment includes a lower jacket section 20 which is supported onsupports 21 (FIG. 6) and an upper jacket section 27. Similarly, theguide member has a lower section 39 and an upper section 38 whichtogether bound a channel for receiving the rod-shaped workpiece 23therein. Hollow tubes 5' and 6' support the guide section 28 in thejacket section 27, and hollow tubes 7' and 8' support the guide section39 in the jacket section 20.

An inclined storage portion 22 for supply of the rod-shaped workpieces23 extends parallel to the lower jacket section 20. A plurality of lugs29 is connected to and projects transversely of the lower jacket section20, and a shaft 28 is supported thereon for rotation about its axis. Aplurality of cams 30 is supported on the shaft 28 for shared rotationtherewith, and at least one lever 27 is connected to the shaft 28 forangular displacement therewith. A link 25 is pivoted to the lever 27 at26 and carries a support pivot 33 at its other end. A plurality of lugs36 connected to the lower jacket section 20 supports a shaft 35, and atleast one lever 34 is provided which is pivotably connected to the link25 by means of the support pivot 33 and is also connected to the shaft35 for angular displacement therewith.

Finally, a plurality of lugs 34 is connected to the upper jacket section37 and also to the shaft 35 for rotation therewith. An electromagnet 24is rigidly connected to the lower support section 20 underneath the sameand has a projection which abuts against the link 25.

A plurality of pins 31 is supported in the portion 22 for axialmovement, all of the pins 31 being in contact with one of the rod-shapedworkpieces 23 and each of the pins 31 being urged by a spring 40 intocontact with the respective cam 30.

The above-described arrangement operates as follows:

When the channel bounded by the guide sections 38 and 39 is empty, aconventional sensing arrangement which need not be discussed in anydetail detects this situation and energizes the electromagnet 24 whoseactuating part then moves in the direction of the arrow 19, that isleftwardly in FIG. 8. Thus, the link 25 is displaced also in theleftward direction which causes the lever 27 and the shaft 28 connectedthereto to rotate in a clockwise direction so that the contact surfaceof each cam 30 moves the associated pin 31 against the force of thespring 40 generally in the upward direction so that the pins 31 lift therespective rod-shaped workpiece 23 off the inclined portion 22 andbeyond an edge 32. Simultaneously therewith, the movement of the link 25causes the lever 34 and the shaft 35 to also rotate in the clockwisedirection so that the lugs 34 are also rotated in the same directionwith attendant movement of the jacket or support section 37 into itsopen position. Thus, the respective workpiece 23 which is lifted overthe edge 32 rolls on the inclined surface and into the guide channel.Once the workpiece 23 is accommodated in the semi-circular channel ofthe guide section 39, the electromagnet 24 is deenergized so that thelink 25 and the parts connected thereto return into their originalpositions illustrated in FIG. 8 so that the workpiece is fullyaccommodated in the channel.

Similarly to the embodiment described previously, the sections 20, 37,38, and 39 as well as the hollow tubes 5', 6', 7' and 8' are coextensivein the longitudinal direction thereof. The hollow tubes 5' and 6' holdthe guide section 38 in the jacket or support section 37, and the hollowtubes 7' and 8' hold the guide section 29 in the jacket or supportsection 20, in coaxial relation with respect to one another.

In order to prevent displacement of the hollow tubes 5', 6', 7' and 8'with respect to the jacket sections 20 and 37 when the sections are intheir open position, the sections 37 and 20 are formed with dove-tailedrecesses 35 and the hollow tubes 5', 6', 7' and 8' are provided withdove-tailed projections 44 which are lodged in the recesses 45. On theother hand, the guide sections 38 and 39 are formed with recesses intowhich the hollow tubes 5', 6', 7' and 8' enter when they are chargedwith pressurized medium, which recesses serve the purpose of assuringthe proper position of the guide sections 39 and 38 with respect to thejacket sections 20 and 27, respectively.

The oscillation-damping hollow tubes 5', 6', 7' and 8' are made of anelastic material and are closed at their ends which face the machinetool A. At the other ends, the hollow tubes 5', 6', 7' and 8'communicate with the supply conduit 9, and the communication will now bedescribed in detail with reference to FIG. 9. Since the pressurizedmedium supply and valve arrangement of this embodiment is the same asthat described previously in connection with FIGS. 1 - 5, this part ofthe supply system will not be repeatedly discussed. It suffices to saythat the conduit 9 is subdivided into two branches 41' and 41" each ofwhich can be separately controlled by means of valves 46' and 46". Thebranch 41" communicates with the hollow tubes 7' and 8', whereas thebranch 41' communicates with the hollow tubes 5' and 6'. Respectivemeasuring devices 12' and 12" communicate with the respective branches41' and 41" and indicate the pressure prevailing therein. Inasmuch asthe lower part of the assembly is stationary, the branch 41' can berigid; on the other hand, the upper half of the assembly is mounted onthe lower part for pivoting with respect thereto, so that the branch 41'has to include at least a flexible portion 42 which compensates for thedisplacement of the upper part of the assembly. As a result of thisarrangement, the guide sections 28 and 39 can be replaced individually.

Because it is necessary to prevent energization of the machine tool A aslong as the pressure in either of the branches 41' and 41" is below acertain threshold valve, two pressure operated switches 15' and 15" areprovided each associated with one of the branches 41' and 41", and theiroperation and cooperation with the contact elements 15' and 15" aresimilar to those of the pressure-operated switch 15 described previouslyexcept that both contact elements 15' and 15" must be in their closedpositions in order to be able to commence the operation of the machineA. The operation of the three-position four-port valve 10 is the same asalready discussed above in connection with the embodiments of FIGS. 1 -5. This valve 10 is again mounted for movement between three positionsO, E and D, wherein the conduit 9 does not communicate with either thepump 11 or with the reservoir 14 when the valve is in the position O,wherein pressurized medium is supplied to the conduit 9 from the pump 11when the valve 10 is in its position D, and wherein the pressure in theconduit 9 is relieved when the valve 10 is in its position E.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofsupport and guide arrangements, differing from the types describedabove.

While the invention has been illustrated and described as embodied in anarrangement for feeding rod-shaped workpieces to a machine tool, it isnot intended to be limited to the details shown, since variousmodifications and structural changes may be made without departing inany way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:
 1. In an arrangement for feeding rod-shaped workpieces to amachine tool, a combination comprising an elongated hollow guide memberfor accommodating a respective workpiece therein; support meansextending longitudinally of said guide member and surrounding the samewith spacing; and a plurality of elongated elastically yieldable hollowtubes filled with pressurized fluid, said tubes extending longitudinallyof said guide member in said spacing and being operative for supportingsaid guide member on said support means and for damping oscillations towhich said guide member is subjected during the operation of thearrangement so as to prevent transmission of the oscillations to saidsupport means.
 2. A combination as defined in claim 1, and furthercomprising means for supplying the pressurized fluid into, andwithdrawing the same from, said hollow tubes.
 3. A combination asdefined in claim 2, wherein said last-mentioned means includes a sourceof the pressurized fluid; and valve means for controlling the supply ofthe pressurized fluid to, and withdrawal thereof from, said hollowtubes.
 4. A combination as defined in claim 3, wherein said valve meansincludes at least two valves for independently controlling the pressureof said pressurized fluid in at least two sets of said hollow tubes. 5.A combination as defined in claim 1, and further comprising means forindicating the pressure in said hollow tubes.
 6. A combination asdefined in claim 1, and further comprising means for detecting thepressure in said hollow tubes and for energizing the machine tool independence thereon.
 7. A combination as defined in claim 6, wherein saiddetecting means includes a pressure switch in the electric circuit ofthe machine tool and operative for interrupting said electric circuit aslong as said pressure in said hollow tubes is below a threshold value.